fix: prevent agent progress layout jitter

The previous popLayout stabilization kept margin-based spacing, so exiting rows temporarily added 6px to bounded Agent lists.

Use flex gaps and a geometry regression check so exited rows no longer change container height.

features/agent/components/agent-message-details.tsx

@@ -237,7 +237,7 @@ function ProgressList({ progress, running }: { progress: AgentChatProgress[]; ru
           <motion.ol
             key={listMode}
             aria-label={expanded ? "全部执行进度" : "最近执行进度"}
-            className="mt-2 space-y-1.5 overflow-hidden"
+            className="mt-2 flex flex-col gap-1.5 overflow-hidden"
             initial={{ height: 0, opacity: 0 }}
             animate={{ height: "auto", opacity: 1 }}
             exit={{ height: 0, opacity: 0 }}
@@ -379,7 +379,7 @@ function PermissionList({
 }) {
   return (
     <AgentNestedBlock icon={LockKeyhole} iconClassName="text-orange-600" title="权限请求">
-      <motion.div className="space-y-1.5" variants={agentPanelListVariants} animate="animate">
+      <motion.div className="flex flex-col gap-1.5" variants={agentPanelListVariants} animate="animate">
         <AnimatePresence initial={false} mode="popLayout">
           {permissions.slice(-4).map((permission) => (
             <AnimatedDetailItem key={permission.requestId}>
@@ -496,7 +496,7 @@ function QuestionList({
 }) {
   return (
     <AgentNestedBlock icon={HelpCircle} iconClassName="text-blue-600" title="补充信息" floating>
-      <motion.div className="space-y-1.5" variants={agentPanelListVariants} animate="animate">
+      <motion.div className="flex flex-col gap-1.5" variants={agentPanelListVariants} animate="animate">
         <AnimatePresence initial={false} mode="popLayout">
           {questions.slice(-3).map((request) => (
             <AnimatedDetailItem key={request.requestId}>